Balloons coated with paclitaxel containing formulations are known. In some cases paclitaxel has been applied directly to the balloon or to a coating placed on the balloon. In other cases paclitaxel has been formulated with an excipient that may be polymer, a contrast agent, a surface active agent, or other small molecules that facilitate adhesion to the balloon and/or release from the balloon upon expansion. The formulations have typically been applied from solution, and may be applied to the entire balloon or to a folded balloon, either by spraying, immersion or by pipette along the fold lines.
Paclitaxel coated balloons that provide high release rates from the balloon surface have recently been developed. However these balloons do not yet provide for delivery of predictable amounts of the drug to the tissue at the delivery site nor do they provide for a predictable therapeutic drug tissue level over an extended time period.
Earlier investigations of paclitaxel coated balloons by the applicant have shown that it is desirable to control the morphology of the drug on the balloon, that dihhydrate paclitaxel crystalline form facilitates longer tissue residence time, and that the formation of crystalline paclitaxel dihydrate can be controlled by use of vapor annealing of the balloon. U.S. application 61/172,629 filed Apr. 24, 2009 describes this work in more detail and is incorporated herein by reference in its entirety.